Crews continue to battle a wildfire in the Verdant Creek area west of Calgary, which has forced the closure of parts of Banff and Kootenay National Parks and prompted air quality alerts for much of southern Alberta.

First spotted on Saturday morning, the fire was estimated to be between 150 and 200 hectares.

Officials said it grew in size overnight but conditions were too smoky on Sunday to estimate its size.

"It's a very narrow valley with very steep terrain so it's not safe at this time to put crews on the ground," said Jane Park, incident commander for the fire.

"We've primarily been actioning the fire through bucketing with helicopter resources. We've managed to work on some of the flanks we're trying to keep from spreading … but it's fairly difficult with these conditions and the wind we're experiencing right now."

A map showing the closed areas of Banff and Kootenay National Parks. (Parks Canada)

"Individuals may experience symptoms such as increased coughing, throat irritation, headaches or shortness of breath," reads the statement. "Children, seniors, and those with cardiovascular or lung disease, such as asthma, are especially at risk."

Several popular hiking trails in Banff and Kootenay National Parks are closed until at least Tuesday and backcountry reservations have been cancelled because of the fire.

In Kootenay National Park, the area closure includes the Honeymoon Pass/Verdant Creek and Simpson River trails.

In Banff National Park, the closure includes all of the Egypt Lake trails, including Healy Pass, Simpson Pass, Whistling Valley and Pharoah Creek.

Those with backcountry reservations in the closed areas should contact 403-762-1556 or visit the Banff National Park Visitor Centre.

The fire is about 10 kilometres northwest of the Sunshine Village ski area, said Park, however that remains open.

Smoke and flames can be seen from the Verdant Creek fire. (Parks Canada)

Shadow Lake Lodge and other tourism operations in the area are also open. Hawk Creek Trail to Ball Pass as well as Redearth Trail to Ball Pass both remain open. Highway 93 South also remains open to vehicle traffic.

The surrounding communities of Banff, Lake Louise and Radium Hot Springs are not at risk.

Parks Canada crews are also battling small wildfires in the Amiskwi Valley and Emerald Lake areas of Yoho National Park, however there are currently no associated area closures.

Smoke can be seen from the Verdant Creek fire, currently affecting Banff and Kootenay National Parks. (Parks Canada)

It was a hazy, smokey sunrise over Calgary on Monday, seen here from Nolan Hill in the city's far northwest. (Matt Melnyk)